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<DIV>And hence my question from yesterday or whenever: ".....is =
<U>+</U>3% of
target mc good enough when drying a board down to produce =
"consistent"
results"? I just don't know how much leeway we commonly have =
to
produce consistent results. When I do something for the first time, I =
tend to
error toward the overkill end of the spectrum, hence my persistent =
questioning.
Thanks for your post, I think I have the info I need now. </DIV>
<DIV> </DIV>
<DIV>Terry Farrell</DIV>
<DIV> </DIV>
<DIV>Below is my post from the other day:</DIV>
<DIV> </DIV>
<DIV>The little cheapies seem to run in the +5% RH accuracy range. That =
is too
inaccurate for drying a board (I think!). With that inaccuracy, if one =
were
shooting for a moisture content of 6.5%, the best you could do is to get =
it
somewhere between 5.8% and 7.2% moisture content. I would like to get it =
closer
to target than that. SNIP One with RH reading accurate to =
within +2%
will get me to within a mc of 6.2% to 6.8% if my target is
6.5%.<BR> <BR>Hey Del or Ron, is <U>+</U>3% of target mc good =
enough when
drying a board down to produce "consistent" results?<BR></DIV>
<DIV>----- Original Message -----
<DIV>From: "Ron Nossaman" <<A
href="mailto:RNossaman@cox.net">RNossaman@cox.net</A>></DIV>
<DIV>To: <<A =
href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>></DIV>
<DIV>Sent: Friday, August 30, 2002 9:48 AM</DIV>
<DIV>Subject: Re: Hygrometer</DIV></DIV>
<DIV><BR></DIV>
<DIV>> How "good" is "good", and how critical is absolute accuracy to =
your
purpose <BR>> and process? No two pieces of wood are going to react =
quite the
same to <BR>> humidity changes, so your chosen material is every bit =
as much
a detriment <BR>> to "accuracy" as a cheap hygrometer. You can buy a =
decent
sling <BR>> psychrometer for something in the $80-$100 range and use =
it as a
cross <BR>> check and calibration device for your cheapie, for your =
own
information and <BR>> peace of mind. You can also use various =
saturated salts
to calibrate. Try <BR>> <A
href="http://www.natmus.dk/cons/tp/satslt/satsalt.htm">http://www.natmu=
s.dk/cons/tp/satslt/satsalt.htm</A>
.<BR>> <BR>> As I said, the most effective way around the need for =
absolute accuracy is <BR>> to build soundboard assemblies that are =
more
tolerant of minor <BR>> irregularities. I dry panels down with a =
little space
heater using the <BR>> piano as my hot box. The panel lays on top of =
the rim,
the heater goes <BR>> underneath, and moving pads go over the top. My =
little
+-2% hygrometer sits <BR>> on top of the panel, under the pads. A =
couple of
days later (depending on <BR>> the season), when it's showing 30%RH, =
the
panel's ready to work. The <BR>> piano's probably a little smaller =
too, but
that doesn't seem to be a <BR>> problem. If I was running a high =
volume
operation, I'd have more floor <BR>> space and build a dedicated box, =
but I
don't expect the basic system would <BR>> be much more sophisticated =
than
what I'm using now except for controlling <BR>> the heat source with =
a
humidistat - and not shrinking the piano too, of <BR>> course. I'd =
prefer
this, since the panel could "soak" a while longer than a <BR>> couple =
of days
and more nearly stabilize, but I haven't noted any problems <BR>> =
from the
rather crude and inelegant way I do it now.</DIV>
<DIV>> <BR>> Ron N<BR>> <BR>> </DIV></BODY></HTML>